Blender - b Why blender is quiting?
The -b command line option tells Blender to run from the command line. But it expects you to pass on a further sequence of commands. If you don't, Blender just quits because you gave it nothing to do.

Also note that the order of commands matters. blender -b -S Scene2 filename.blend -a for instance will open the default scene, then try to switch to Scene2 (which won't exist), then open filename.blend, and then render the frame range defined in the file. After that it quits. blender -b filename.blend -S Scene2 -a will on the other hand first open the file filename.blend, THEN switch to Scene2, then render the animation.

See the manual for more information on this matter:

https://docs.blender.org/manual/en/2.80/advanced/command_line/launch/index.html
https://docs.blender.org/manual/en/2.80/advanced/command_line/arguments.html